This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A071009 #3 May 10 2013 12:45:01 %S A071009 1,4,16,48,119,256,500,900,1525,2456,3796,5664,8207,11588,16004,21672, %T A071009 28845,37800,48856,62356,78691,98280,121592,149128,181445,219132, %U A071009 262840,313256,371131,437256,512492,597740,693977,802224,923580 %N A071009 Number of solutions (x,y,z,u,v,w) to x+y+z = u+v+w, 0<=x,y,z,u,v,w<=n-1, x>=y>=z, u>=v>=w. %F A071009 Recurrence: a(n) = 3*a(n-1)-a(n-2)-4*a(n-3)+2*a(n-4)+2*a(n-5)+2*a(n-6)-4*a(n-7)-a(n-8)+3*a(n-9)-a(n-10). G.f.: x*(1+x+5*x^2+8*x^3+5*x^4+x^5+x^6)/(1+x+x^2)/(1+x)^2/(1-x)^6. %Y A071009 Cf. A071816. %K A071009 nonn %O A071009 1,2 %A A071009 _Vladeta Jovovic_, Jun 10 2002